Method of treating aluminium or aluminium alloy



April 28, 1936. HAYAKAWA 2,039,165

METHOD OF TREATING ALUMINIUM OR ALUMINIUM ALLOY Filed Jan. 17, 1935 INVEN TOR.

KAZUMA HAVA KAWA BMMQLZ A TTORNEYS.

Patented first. 28, 1936 PATIENT I OFFICE METHOD or TREATING ALUMINIUMon ALUMINIUM ALLOY 1 K'azuma Hayakawa, Hodogaya-ku,

Yokohama, Japan App ication January 17, 1935, Serial No. 2,171 2Clalm's. (CI. 75-68) The present invention relates to a method oftreating aluminium or aluminium alloy which is based on the knowledgethat when the gas contained in aluminium or aluminium alloy is liberatedby heating them in vacuum, it reacts with aluminium and iron andproduces various compounds having high hardness and that said compoundsare turned into fine particles by ageing and distributed all over thealuminium or aluminium alloy, thus producing "aluminium or aluminiumalloy having high hardness as a whole, characterized by the fact thatmolten aluminium or aluminium alloy is put into an iron vessel andheated in vacuum for thirty to sixty minutes at a temperature above 900C., after which the heating temperature is lowered to 500 to 700 C. andhydrocarbon gas is filled in the vessel up to more than 1 atm. and thenthe material is cooled rapidly.

The object of this invention is to obtain aluminium or aluminium alloyhaving high hardness simply by considerably increasing the hardness ofaluminium or aluminium alloy easily and effectively.

Generally, aluminium solution possesses the property of absorbing a gasvery much, so it is made to be able to absorb in a molten state a gashaving the volume and at the higher temperature it can absorb the biggerquantity. According to Gwyer (Trans.

Faraday Soc. 1919,-vol. 14, p. 173), the following ases were absorbed:--

Percent Carbon dioxide 3 8 Carbon monoxide 0 9.5

Hydrogen -81 Methane 1 -24.5

Nitrogen 5 -11 Oxy 1.5- 4.5

When the free carbon thus produced comes into contact with aluminium invacuum, it will produce crystals of A140: at 650 C. On the other 55hand, aluminium has iron melted thereinto at a high temperature in thepresence of hydrogen and produces FeAls. Consequently, hard compounds,namely,FeAla, A140: and A: are dis stributed in aluminium or aluminiumalloy at a high temperature and are present therein in a I saturatedcondition. However, if cooled rapidly, they take an oversaturatedcondition at the ordinary temperature and then, with the lapse of time,are turned into a fine state and separated from the solid solution.Thus, it is possible to ob- I. tain aluminium or aluminium alloy havinghigh hardness.

Referring to the appended drawing,

Fig. l is a longitudinal elevation of an apparatus employed for carryingout this invention into practice;

Fig. 2, a section cut off along the line II-II of Fig. 1 and Fig. 3, asection showing the condition in which fine crystals of FeAla, AhCa andA: have been distributed in aluminium metal and hardened very high.

I To explain the present method with reference to the accompanyingdrawing,

In Figure 1, I is an ingot of aluminium or aluminium alloy; 2, an ironvessel, for example, an iron pot; 3, an electric resistance furnace and4, the part where two flat surfaces are connected together by friction,8 is a porcelain tube for supporting the lead wire I of said electricresistance furnace 3, said lead wire I being cemented to said tube 6 atits end with Dekotinsky cement.

8 is a water jacket; and 9, an empty chamber to be rendered vacuous orcooled as is necessary. If air is exhausted from tubes l4 and is,closing cocks III, II and i2 and opening a cock i3 and operating an airpump (not shown), the above empty chamber 9 will be rendered vacuous.Reversely, if water is introduced into said chamber 9 from a conduit l6,closing the cock l3 and opening the cooks l0 and I l, and then thefilling water is discharged from an exhaust pipe i1 through the cock Ii,it is possible to cool the chamber. I8 is a heat resisting steel plateadapted for preventing the deformation of the furnace wall by reflectingheat. I9 is a heat reflecting'plate consisting of a round heat resistingsteel plate having apertures 20 and a heat resisting steel plate of thesmaller diameter, combined to form an I-shaped section. It is engagedwith the projections 2| of the upa per part of the inner wall of thefurnace and is suspended over the iron pot 2. The exhaust of the air inthe furnace is effected from a tube I! through the apertures 20 of theheat reflecting plate It by means of an air pump (not shown).

Also, to fill hydrocarbon gas in the furnace, it is introduced into thelatter from the tube I! through a tube 22 and the cock i2.

The following is the manner of performing this invention by employingthe above apparatus:-

Firstly, closing the cocks III, II and I2 and opening the cock is,exhaust air from both the furnace and empty chamber 9 by an air pumptill they become partially vacuous, when the interior of the furnace isheated by the electric resistance furnace 3, and as the empty chamber 9is at this time in a vacuous state, it prevents the escape of heat fromthe electric furnace 3. Thus, after melting aluminium or aluminium alloyby heating it in the iron pot 2 for thirty to sixty mihutes by saidelectric furnace, lower the temperature to 500-700 C. by regulating thevoltage of the electric furnace. Then, fill hydrocarbon gas in thefurnace up to over 1 atm. through the tube I. from the tube 22 byopening the cock l2. Soon after, opening the cocks l0 and Ii and closingthe cocks l2 and i3, introduce cooling water into the empty chamber 9from the tube II and discharge it from the tube i1, thus cooling saidmolten aluminium or aluminium alloy rapidly.

The aluminium or aluminium alloy thus obtained having fine crystals ofFeAla, AliC: and

aosaios A120: distributed all over them as shown in Figure 3, possessesvery high hardness.

In Figure 3, 23 is the outer cylindrical part of an iron vessel havingthe hardness l0.2 accord ing to Rockwell scale. 20 is the aluminiummetal manufactured according to the present invention, the hardness ofthe diflerent parts of which, when measured with Rockwell scale, has thevalues as shown in Fig. 3.

I claim:

1. Method of treating aluminium or aluminium alloy, which consists inheating molten aluminium or aluminium alloy in vacuum in an iron vesselfor thirty to sixty minutes at over 900 C., then lowering the heatingtemperature to 500 to 700 C. and filling hydrocarbon gas in said vesselup to over 1 atm. and subsequently cooling the above material quickly.

2. Aluminium or aluminium alloy having high hardness, which is made byheating molten aluminium or aluminium alloy in vacuum in an iron vesselfor thirty to sixty minutes at over 900 C., then lowering the heatingtemperature to 500 to 700 C. and filling hydrocarbon gas in said vesselup to over 1 atm. and subsequently cooling the above material quickly.

KAZUMA HAYAKAWA.

